'73 Model-T 6550/el34 conv.

[Peter S]

Can someone tell me how to convert a '73 Model-T from 6550's to el 34's? My question is mostly in regards to whether or not this has a truly adjustable bias or is it merely a bias ballance as in the case of my Silverface Twin Reverb. The amp still sounds killer but it has the original Tung-sol tubes and I think they might be a bit tired and thought if I was going to have to replace them anyway, maybe I'd give the 34's a shot.
Thanks!

[George Snyder]

Peter:
I think the older Sunn amps with EL34's had lower plate voltages that those with 6550's. My Sceptre puts 550v on the plates of its 6550's and I think this is beyond spec for EL34's. You might consider KT88's as an alternative. Some folks on this board have had good things to say about them. I hope to try them myself in the not too distant future.

George